Corrugated sheet metal structure



Oct. 24, 1939. c. DE GANAHL 2,177,473

- CORRUGATED SHEET METAL STRUCTURE Filed March 25, 1937 INVENTOR 617/?1. ziflmwm ATTORNEY- Patented Oct. 24, 1939 PATENT OFFICE 2,177,478 CORRUGATED SHEET METAL STRUCTURE Carl de Ganahl, Bristol, Pa., assignor to Fleetwings, Inc., Bristol, Pa., a corporation of Delaware Application March 25, 1937, Serial No. 132,915

12 Claims.

This invention relates to corrugated sheet metal structures, and particularly to sheet metal assemblies for aircraft.

In structural members incorporating corrugated sheets for reinforcing or other purposes, it frequently happens that the corrugated sheets are used alone with relatively inclined side edges or on members which taper or are otherwise of different widths at different parts of the structure. With corrugated sheets having conventionally parallel corrugations extending longitudinally of the sheet, the angularly divergent side edges provide a structure which requires fewer corrugations at one portion than at another.

ll When this is secured by cutting the corrugated sheet on a line angularly divergent from but intersecting the corrugations, there is formed an undesirable unfinished open edge of elongated cut corrugated portions, which cannot be satisfactorily fastened to the remainder of the element, andQwhich therefore comprises an item of weakness, which is open or scalloped at the edge instead of being a longitudinal straight line edge as can be secured cm the opposite side edge of the sheet.

It isamong the objects of this invention; to provide 'an improved method of fading out corrugations insheet metalito provide a corrugated sheet metal structure in which two side edges are mutually non-parallel, but are each parallel to one or more corrugations in the sheet; to provide a terminal piece having stepped or staggered rudimentary corrugations arranged to be registered with the ends of staggered or stepped corrugations in a main sheet; to provide a terminal piece having a side edge to which one side of a rudimentary fading out corrugation is substantially parallel, and a main sheet having a side edge parallel to corrugations in the sheet and to which the other side of said rudimentary fading out-corrugation is substantially parallel; to provide a corrugated sheet of enhanced visual attractiveness; and many other objects and advantages as will become more apparent as the description proceeds.

In the accompanying drawing: Fig. 1 represents a plan of an illustrative assembly of a main sheet and a terminal strip,

Fig. 2 represents a plan of the elements of Fig.

and having any desired number of corrugations I I, all preferably and usually, although not necessarily, extending parallel tothe margin or finished lateral or side edge I2. Edge I2 is usually a finished edge to be secured to the remainder of the structure as by rivets or spot welding, or the like, and is formed by cutting longitudinally through a corrugation, or by a fiat margin or the like. It may be assumed that the requirements are such that a finished side edge opposite from edge I2 is to be provided andthat it is angularly divergent from edge I2. This situation could be found, illustratively, in the use of the sheet) as a reinforcement or a web for a wing spar, or the like. If the corrugations II were severed by an angular cut representing the opposite finished edge, angularly divergent, and spaced by the width of sheet I0, from edge I2, it would be evident that there would be no finished edge surface, such as the substantial center or any other predetermined line of a corrugation, extending full length of the sheet, by which the opposite edge could be anchored in place to carry and distribute the stresses of the sheet. The scalloped edge formed by such cut would form a focus of stresses such as to cause disruption under strains.

As a prelude to the association of the main sheet with a finishing terminal piece, according to this invention, the sheet I0 is cut away opposite to finished edge I2 to form a series of steps comprising respectively an edge I3 cut, or otherwise formed, longitudinally of the sheet just beyond the center of the apex of a desired given corrugation, parallel to the edge I2, terminated by a transverse substantially perpendicular shoulder or edge I4, merging into a secondary side edge I5 closer to edge I2 than edge I3, and by a secondary transverse shoulder I6 longitudinally spaced from shoulder I4, into the next longitudinal edge II, again still closer to edge I2 than edge I5, terminating in longitudinally spaced tertiary shoulder I8, etc., depending upon the length of the sheet. Each transverse shoulder I4, I6 and I8, etc., contains the edge of one complete corrugation II, presenting in the same direction perpendicularly of the sheet.

The finishing or terminal strip 9 comprises a finished edge I9, adjacent and substantially parallel to which any desired number of corrugations 20 may be formed. One double corrugation 20 is illustratively shown. The strip 9, opposite to the finished edge I9, is formed into a saw-tooth plan form, of staggered step construction comprising integral triangular parts 2|, the apices of which are close to the line of corrugation 2|, while the bases comprise substantially parallel longitudinally spaced edge surfaces respectively 22, 23 and 24 connected longitudinally by the step edges 25, 26, 21, etc., each of which is angularly divergent from edge l3.

Each triangular portion 2| contains a rudimentary abbreviated tapering root corrugatiomrs, which'is of full depth at the edges is,

23, etc., and for a short longitudinal distance toward the apex of the triangular portion, as indicated at 30, is a corrugation which is angularly divergent from corrugation 29 by an angle similar to that to be secured between the-finished edges of the composite sheet, and of a length sufiicient to permit the nested registration therer with of the end of the appropriate corrugation Ill in the main sheet, at its termination in the respective shoulder or transverse edge M, II, etc. From the short distance inwardly of the-edge 22, 23, etc., the metal is drawn or forced into a tapered continuation 3| of the short'full depth root 30, which has one wall substantially parallel to edge l9, and the other to step edge 2', 28,. etc.,

which beingconvergent finally merges or disappears into the unbroken plane portion of the apex 32 of the triangular part 2|. There will be 88 many of the abortive or rudimentary root coretc., out of the plane 2|, into lateral registration with corrugation ll.

The stresses in the main sheet carried by the corrugations are dissipated in the finishing" strip;

The complete assembled job provides a sheet of corrugated material of enhanced attractiveness having a pair of spaced non-parallel finishing edges and is of great strength, and when joined by overlapping spot welds or, seam welding. provides a liquid tight seam of great strength. The invention is of particular value in finishing sheets of hard stainless steel and the like.

I claim: K

1. A composite corrugated structure compris ing a pair of superposed overlapping sheets havingacutely angularly divergent lateral ed es in near parallelism, corrugations parallel to one edge in one sheet terminating in tapering terminal corrugations spaced from'both edges within the other sheet in staggered longitudinally spaced relation.

2. A composite corrugated structure comprising a pair of contacting overlapping sheets having angularly divergent lateral edges, a corrugation formed in and extending longitudinally of the structure parallel to each such edge, a second corrugation extending parallel to one edge and shorter than the first mentioned corrugations disposed in one sheet and terminating in a tapered fading out end corrugation in the other said sheet.

3. A corrugated structure comprising a sheet having acutely angularly. divergent lateral edges.

a pair of corrugations formed in and extending longitudinally of the sheet respectively parallel to each such edge, a second corrugation extending parallel to one edge and shorter than the first mentioned corrugations'terminating in a tapered fading out end corrugation in the sheet, said tapered fading out end corrugation comprising lateral portions substantially parallel to each of said edges so as to fade 'out to a substantial point to substantially fill the space between the said corrugations.

4. A corrugated structure comprising asheet having acutely angularly divergent lateral edges, a corrugation parallel to one edge terminating in a tapering terminal corrugation within the sheet of shorter extent than the sheet, and said tapering terminal having lateral portions substantially parallel to both said lateral edges so as to fade out to a substantial point in alignment with one side of the first mentioned corrugation.

5. In corrugated structures, a sheet comprising a plurality of overlapping elements, the sheet having almost parallellateral acutely convergent edges formed in' different elements respectively,

a corrugation formed in the sheet parallel to onev edge in one element, a second corrugation formed in the sheet substantially parallel to the first corrugation and formed in the same said' element,

' said second corrugation having a tapered end and fading out of existence in another'element of said sheet in spaced relation to-both of said 8. In corrugated structures, a composite sheet 7 comprising a plurality of overlapping elements, the sheet having lateral acutely 'convergent edges in near parallelism, acorrugation formed in the sheet parallel to one edge, a second corrugation formed in the sheet substantially parallel to the first corrugation but of shorter longitudinal extent, said second corrugation having a tapered end and'fading out of existence in said sheet, said tapered end formed'in an elementdiflerent from the element containing the remainder of said second corrugation and-spaced from both of said edges. v

.7. In corrugated structures a finishing strip comprising a substantially triangular integral portion having a finished edge and an edge angularly divergent from the finished edge and a base edge angularly divergentfrom the first mentioned divergent edge, the triangular portion having adjacent the base edge a rootcorrugation formed on a center angularly divergent from said finished edge, saidroot corrugation merging into a tapered fading out extension in the triangular portion and arrangedto form the terminus of a substantially aligned corrugation in an associated overlapping sheet. I

8. In corrugated structures a finishing strip comprising a substantially finished edge, a substantially triangular integral portion having an ished edge and a base edge substantially normal to the divergent edge, the triangular portion having adjacent the base edge a root corrugation formed on a center acutely angularly divergent from said finished edge, said root corrugation merging into a tapering fading out extension in the triangular portion comprised of surfaces I edge acutely a'ngularly divergent from the finsubstantially parallel to both the finished and divergent edges.

9. In corrugated structures a finishing strip comprising a substantially finished edge, a substantially triangular integral portion having an edge acutely angularly divergent from the finished edge and a base edge substantially normal to the divergent edge, the triangular portion having adjacent the base edge, a root corrugation formed on a center acutely angularly divergent from said finished edge, said root corrugation merging into a tapering fading out extension in the triangular portion comprised of surfaces substantially parallel to both the finished and divergent edges, and a complemental sheet comprising a finishing edge, a corrugation substantially parallel thereto, a secondary corrugation terminated by a transverse edge substantially perpendicular to the first corrugation.

10. In corrugated structures a finishing strip comprising a substantially finished edge, a substantially triangular integral portion having an edge acutely angularly divergent from the finished edge anda base edge substantially normal to the divergent edge, the triangular portion having adjacent-the base edge a root corrugation formed on a center acutely angularly divergent from said finished edge, said root corrugation merging into a tapering fading out extension in the triangular portion comprised of surfaces substantially parallel to both the finished and divergent edges, and a complemental sheet comprising a finishing edge, a corrugation substantiallyparallel thereto, a secondary corrugation terminated by a transverse edge substantially perpendicular to the first corrugation, said complemental sheet superimposed upon said finishing strip with the secondary corrugation end nested in the root corrugation and with the tapering end forming a terminal for said second corrugation, and means rigidly securing the strip and sheet together.

11. A corrugated sheet constituted by a finishing strip comprising an edge, a saw-tooth edge spaced from the first edge, rudimentary corrugations in the respective saw-teeth taperingly fading to a substantial plane, a corrugated sheet having staggered edges transverse of corrugations, and means joining the corrugated sheet and strip so that the rudimentary corrugation is aligned with a corrugation in said staggered edge. a

12. A corrugated sheet metal structure comprising a metal sheet having an edge and a tapered short corrugation merging at its sub stantially pointed end into the surface of the sheet and at the other end into a straight corrugation ending in the edge of the sheet, a second edged sheet having a corrugation terminating in the edge, the said edges of the sheets disposed -in overlapping relation with the straight portions of the corrugations in nested aligned relation, and means securing the overlapping portion of the sheets together, the .first and second sheets having external nearly parallel but slightly divergent lateral edges of which one is parallel to said straight corrugation, and said short 39 corrugation being spaced from both lateral edges. CARL m: GANAHL. 

